I'm thinking mostly it's a vibe damper, but...
That being said, the third that my 4:77's came in had no such monkey block, being from an older Trooper.
I thought about changing the R & P from the old Trooper casting, into the one form my VX, but quickly talked myself out of that, as it would entail setting up the gears, pressing bearings on & off, yadda-yadda-yadda...that all added up to extra time & expense that I preferred not to spend.
Bottom line...there is no such block on my current rendition of a front axle assembly, & I have noticed no bad ju-ju because of it.
If anything, the "mystery clunk" that many of us experience upon release of the brakes after coming to a stop, is now a thing of the past.
However, that might be due to re-tightening the trans mount to the trans/cross member, which was done at the same time...